Various industrial applications such as welding cables, mining cables, locomotive cables, automotive battery cables and geophysical cables require cables that have adequate cross-section for current-carrying capacity as well as high flexibility due to the nature of the application and installation. Unlike building wire and power cables, these cables cannot be produced using solid single wires in concentric or unilay configurations. Examples would include 37 or 61-strand MCM unilay cables. To maintain the cross section as well as high flexibility, these cables are produced by having several layers (19, 37, 61, etc.), with each layer comprised of either a group of multi-wires or bunched wires. Higher flexibilities are achieved by using smaller diameter wires and increasing the total number of wires to maintain the cross section. Traditionally, such products have been produced on a planetary cabler. This process poses some critical production issues such as low production speeds, extensive changeover times and short production lengths restricted by the reel size in the cradles. Also, the equipment cost is very high. An alternative to this is to produce these cables on a double twist buncher where the production speeds are very high, longer lengths can be produced and the changeover time is considerably low.
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